Dissolution of or exclusion from important social groups places in social groups places individuals at increased risk of anxiety, dysphoria, depression, and in extreme cases, suicide. The current proposal identified and explores a social process that is hypothesized to foster and sustain intragroup relations, and, consequently minimizes the likelihood that persons suffer the ill consequences of exclusion or ingroup- dissolution. In particular, the planned research develops and tests the Social Regulation Model (SRM) of ingroup favoritism. The SRM is grounded in the assumptions that social groups are vital to human survival, arise from multiple factors, and involve intragroup relations that, at times, give rise to conflicts of interest that threaten the stability of the group and an individual's membership in the group. This model asserts that positive ingroup beliefs and behaviors can occur in the absence of an outgroup and function, in part, to regulate and maintain harmonious intragroup relations. In group favoritism is viewed as an adaptive characteristic of group life in that it promotes trust, reciprocity, and expectations of cooperative interactions among ingroup members. This social regulation component of ingroup favoritism is hypothesized to arise when persons experience a heightened awareness of their shared group membership. Because the SRM recognizes that group formation is a multiply determined phenomenon, awareness of shared group membership can be triggered by multiple factors including, but not limited to, the presence of a contextually relevant outgroup and interdependence among ingroup members. In other words, the SRM asserts that ingroup favoritism has an intragroup component that regulates social relations among ingroup members and is not limited to a situation in which an outgroup is salient. The proposed experiments tests the SRM's assertion that positive behaviors towards the ingroup are part of a social-regulation that maintains harmonious intragroup relations. In particular the experiments test if increasing awareness of shared group membership, in the absence of an outgroup, increases (a) trust among ingroup members, (2) concern for the welfare of ingroup members, and (c) de-escalates intragroup conflict by promoting forgiveness. .